The girl told FBI agents that when she was 15, she worked as a prostitute for D and his girlfriend, whom she knew only as Tara. It was the summer of 2011 and the girl had a client base of 10 to 15 johns that she would service at hotels in Palm Beach County.

These were the first important building blocks of a federal child-sex-trafficking case that would culminate this week with the arrest of Dontavious Mingel Blake and Tara Jo Moore, according to a complaint unsealed Friday in the West Palm Beach federal courthouse.

And although agents spoke to cooperating witnesses, they also took to the Internet and social media in their efforts to track down Blake, 32, and Moore, 26, both of Palm Beach County.

The pair were arrested Wednesday on federal charges of sex trafficking of children, inducing a minor to engage in a commercial sex act, and conspiring to induce a minor to engage in a commercial sex act.

If convicted, they could face life in prison.

Blake has had nine prior arrests since 2000, according to Florida Department of Law Enforcement records; Moore has four prior arrests since 2007.

According to the complaint, the National Center for Missing and Exploited Children forwarded a tip to FBI agents in July 2012. The tip reported that an ad on the online classified site Backpage.com featured a girl under the age of 18 and listed a Miami phone number.

The center identified an I.P. address and email associated with the ad, the complaint states. That email address — snowbunny561@hotmail.com — was searched on Facebook and Myspace.

It lead to a Facebook page for Tara Moore, of West Palm Beach, and a Myspace page for Dontavious Blake. Both social media profiles were still online as of Friday afternoon.

According to Moore's profile, she attended Jefferson Davis Middle School in West Palm in 2000. She lists her occupation as Boss Lady at Tricks R us. A profile picture shows a woman wearing a Miami Heat jersey, short shorts and hair braids, standing in front of a gray car.

Although Blake is a man, his Myspace profile says 'Female, 28, Miami, Florida.' A profile picture, posted in July 2011, shows a female in her bra and underwear striking a sexually suggestive pose atop what appears to be the counter of a hotel bathroom.

In August 2012, according to the complaint, agents were interviewing the underage girl as part of a separate investigation into child pornography.

The girl told them about working as a prostitute for D and Tara. She described D as a muscular, black male with no facial hair who drove a gray Dodge Charger. She said Tara answered the phones for D, handling the escort calls. She said that D "worked approximately four to five girls out of hotels in the Palm Beach County area," including at least one other underage girl, agents alleged.

The girl said she met Blake at a Holiday Inn in West Palm Beach after finding his business card for escort services. She provided pictures to him and he posted the photos in ads for escort services on Backpage.com, booked hotel rooms, and drove the girl to calls in his gray Charger or green Cadillac.

The girl said she shared the money she made with Blake, the complaint states. After she stopped working for him, she said, ads with her picture were still being posted.

In an undercover operation on Sept. 25, 2012, agents stopped Blake as he drove his Charger into a gas station beside a West Palm hotel. They found a business card for Divine Escorts, which listed Blake's cellphone number and the snowbunny561 email linked to the July 2012 tip, Moore's Facebook page and Blake's Myspace profile.

Blake told agents he had no girls working for him and had not posted any escort-related ads to the Internet.

Agents issued a subpoena to Backpage.com and found a Dontavious Blake, of West Palm Beach, had posted escort ads to the site, court filings allege. The info from Backpage also listed a phone number and the snowbunny561 email address.

Interviewed again, the girl was shown a picture of Blake and identified him as the "pimp she knew as D," the complaint alleges. She also identified a picture of Moore as Tara, D's girlfriend.